Relationships between the curing conditions and some mechanical properties of hybrid thermosetting materials

Abstract

Foi investigada a relação entre os parâmetros calor de polimerização (ΔH) e energia de ativação (E a ) obtidos por calorimetria diferencial de varredura (DSC) e a proporção entre resina epóxi e endurecedor de polímeros termorrígidos baseados em uma resina epóxi híbrida orgânica-inorgânica (OG). A energia de ativação (E a ) e o calor de polimerização (ΔH) aumentaram com o aumento do conteúdo de OG até 70% em massa. Um aumento adicional no conteúdo de OG até 80% reduziu E a e ΔH. A análise dinâmico-mecânica sugere que a máxima densidade de ligações cruzadas é obtida em 83% de OG, enquanto as propriedades mecânicas de resistência à fratura e módulo de tensão são maximizadas em tôrno de 70% de OG.The relationship between the heat of polymerization (ΔH) and activation energy (E a ) parameters, obtained by differential scanning calorimetry (DSC) and the ratio of epoxy resin to hardener of the thermosetting materials based on an organic-inorganic hybrid epoxy resin (OG) was investigated. Activation energy (E a ) and heat of polymerization (ΔH) increased with an increasing OG content, up to 70 wt%. Further increase in OG content to 80wt% reduced E a and ΔH. Dynamic mechanical analysis indicates that the maximum cross-link density is obtained at 83 wt% OG, whereas fracture toughness and tensile modulus mechanical properties are maximized at 70 wt% OG.

Recent Developments in the Chemistry of Cubic Polyhedral Oligosilsesquioxanes

“…Several examples of nanocomposites with different amines showing improved physical properties have been reported. ,,,,,,, For example, the copolymerization of epoxide 188 with 4,4′-diaminodiphenylmethane in the presence of DGEBA gave a material with lower T g , better thermal stability, and higher modulus, thought to be arising from the reinforcement effect due to the POSS units . The lifetime of such a system has been calculated, and it was found to be theoretically thermally stable for more than 30 years at 100 °C in the absence of other reagents .…”

“…The specific applications of POSS compounds in polymers and materials are described in detail below, those properties being significantly affected are mechanical properties (refs , , , , , , , , , , , , , , , , , –), tensile modulus (refs , , , , , , , , ), shear modulus (refs , , –), storage modulus (refs , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , –), Young’s modulus (refs , , , , , , ), loss modulus (refs , ), flexural strength (refs , , ), compressive strength (refs , ), hardness (refs , , , , , ), stiffness (refs , , , , ), sheer thinning behavior (ref ), peel strength (refs , –), shear strength (ref…”

Relationships between nanostructure and dynamic-mechanical properties of epoxy network containing PMMA-modified silsesquioxane

“…Consequently an improvement of thermal, oxidative and dimensional stability as well as mechanical performance of many polymeric resins is usually achieved. Mono-and multi-functionalized silsesquioxanes containing epoxy [7,[19][20][21][22][23][24][25][26][27], amino [28][29][30][31][32], mercapto [33], maleimido [34,35], and isocyanate groups [36] have been successfully employed in the preparation of epoxy resin-based hybrid materials. Mono-functionalized silsesquioxanes are prepared by corner capping reaction of a trisilanol with a functionalized trialkoxy silane, and results in POSS molecules grafted onto the epoxy matrix [14].…”